Live attenuated hepatitis A vaccine is recommended to be considered for injection at one and a half years of age or older. After hepatitis A vaccination, patients will have lasting immunity to the hepatitis A virus. The main component is the attenuated pathogen, which is dissolved by water for injection and then administered to the deltoid area. Some patients may have fever and allergic reactions after the injection. If the fever is mild and transient, observation and drinking more water is generally recommended. However, if the fever is more severe, the body temperature is higher or the allergic reaction is more severe, further consultation within the hospital is required to see if there is any possibility of other diseases and if there is severe allergy. If the patient is seriously ill, further anti-allergy treatment is needed. In addition, some patients will form ulcers and lumps on the local skin after vaccination. This condition is mostly seen in some patients who have high immunity and whose body reacts more strongly to antigens, so it is recommended to disinfect locally with iodophor and then cover with band-aids, avoid getting water on the local area as much as possible, and treat for a period of time.